Ballistic Propagation

In salt marshes along the North Carolina coast, marine biologists Jan and Brigitte Kohlmeyer of the University of North Carolina have discovered a genus of fungus that spits to survive. The fungus is named Glomerobolus gelineus, which, roughly translated from Latin, means throws a ball of jelly. It consists of three or four knobs called a hyphoma surrounding a globular propagule. The propagule is what enables the fungus to propagate, as the husband-and-wife team discovered when they put a drop of water on it. All of a sudden the center disappeared and we realized that this thing was shooting, and it shot into the lens of our microscope, says Jan Kohlmeyer. When the fungus is moistened by rain or biologists, it seems, its knobs swell, squeezing the propagule in the center until the pressure pops it out--a bit like squeezing a watermelon seed between your fingers. The fungus gets only one shot; afterward the hyphoma dies. If the propagule chances to land on a dead plant, however, it sinks filaments into the plant tissue and extracts the food energy it needs to grow new hyphomas and propagules. Glomerobolus is able to shoot its propagule at least a foot (that’s the distance across the largest aquarium in the Kohlmeyers’ lab). The propagule is unlike the spores launched by some other fungi: it is a piece of the fungus, rather than a seed with a hard coat, and it allows the fungus to propagate vegetatively like plants that grow from shoots.